This invention relates generally to log handling systems for use in the woods or other elongated object handling systems, but more particularly to a remotely controlled choker hook and release system.
It is common practice in woods operations where trees are being harvested and logs moved about to utilize cable handling systems either at ground level or overhead yarding systems. As a part of these log handling systems, steel cables are wrapped about felled trees to form a noose or choker. The cable, once looped around a tree or a plurality of trees, is attached back onto itself, using a special device referred to as a choker hook which allows the loop to tighten about the tree. The tightened loop serves to hold it as the cable is then tensioned to lift the tree and pull it to the desired location. Once the logs arrive at the desired location, the choker must then be released in order to release the tree. The typical way choker hooks are now released is by manual labor. Physically releasing the chokers can be hazardous, and it takes time and delays production.
In the past, others have designed remotely controlled self-releasing choker mechanisms and one such example may be seen by referring to U.S. Pat. No. 3,104,909 issued in 1963 to W. M. Walker. In the Walker patent, a choker hook is disclosed where the end of a cable has a ferrule or knob affixed to it which is seated and held within the choker hook casing. A pivotally mounted locking arm is controlled in part by a servo for holding and releasing the end of the cable. There are certain shortcomings in the Walker choker hook, among them being its lack of flexibility, openness, complexity, size and cost. These disadvantages have been overcome by the invention disclosed in U.S. Pat. No. 4,417,758--Vaders, assigned to the assignee of the present invention. The disclosure of U.S. Pat. No. 4,417,758 is hereby incorporated herein by reference.
After the remotely releasable choker of U.S. Pat. No. 4,417,758 had been used in the woods certain ideas were conceived to provide improved performance. For example, when operating the radio controlled choker disclosed in the aforementioned patent it was necessary to latch the arm after wrapping the cable about the object and lodging the cable and knob between the the latch arm and choker housing. The operator had to make sure the cable was in place before closing the latch arm. This was in effect a "three handed" operation.
In addition, the cable and knob when locked in place and after tension was applied to lift a load were bent about an angle relative to the latch arm. It was determined this could lead to greater stresses than would otherwise be desirable on the assembly, resulting in kinked cable and the kinked end proved difficult to manipulate under logs.
In U.S. Pat. No. 4,569,548 also assigned to the assignee of the present invention a cocking cam is disclosed that allows an operator to easily cock the slidable pin in place by using the leverage obtained from employing the latch arm as a lever arm. It was determined that while this improvement provided easy setting of the pin it often caused the pin to be driven violently upward thereby resulting in unwanted maintenance requirements.
Thus, from the foregoing, one object of the present invention is to make the cable looping and securing process easier for the operator.
Another object is to reduce the stresses and kinking on the end of the cable below its knob by maximizing the radius over which the cable is bent where it enters the latch arm.
Still a further object is to reduce the rigidity of the cocking cam in order to reduce forces on the slidable pin when it is moved upwardly and locked in place.
These and other objects of the invention will become apparent when reading the specification to follow in conjunction with the attached drawings.